I am following following tutorial to write a custom pallet.
https://docs.substrate.io/tutorials/build-application-logic/use-macros-in-a-custom-pallet/
When I compile the node, I get following error:
error[E0220]: associated type `BlockNumber` not found for `T`
--> pallets/template/src/lib.rs:46:62
|
46 | StorageMap<_, Blake2_128Concat, T::Hash, (T::AccountId, T::BlockNumber)>;
| ^^^^^^^^^^^ there is a similarly named associated type `BlockNumber` in the trait `BlockNumberProvider`
For more information about this error, try `rustc --explain E0220`.
Here are the contents of my pallet lib.rs file that I trying to compile:
#![cfg_attr(not(feature = "std"), no_std)]
// Re-export pallet items so that they can be accessed from the crate namespace.
pub use pallet::*;
#[frame_support::pallet]
pub mod pallet {
use frame_support::pallet_prelude::*;
use frame_system::pallet_prelude::*;
#[pallet::pallet]
#[pallet::generate_store(pub(super) trait Store)]
pub struct Pallet<T>(_);
/// Configure the pallet by specifying the parameters and types on which it depends.
#[pallet::config]
pub trait Config: frame_system::Config {
/// Because this pallet emits events, it depends on the runtime's definition of an event.
type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
}
// Pallets use events to inform users when important changes are made.
// Event documentation should end with an array that provides descriptive names for parameters.
#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T: Config> {
/// Event emitted when a claim has been created.
ClaimCreated { who: T::AccountId, claim: T::Hash },
/// Event emitted when a claim is revoked by the owner.
ClaimRevoked { who: T::AccountId, claim: T::Hash },
}
#[pallet::error]
pub enum Error<T> {
/// The claim already exists.
AlreadyClaimed,
/// The claim does not exist, so it cannot be revoked.
NoSuchClaim,
/// The claim is owned by another account, so caller can't revoke it.
NotClaimOwner,
}
#[pallet::storage]
pub(super) type Claims<T: Config> =
StorageMap<_, Blake2_128Concat, T::Hash, (T::AccountId, T::BlockNumber)>;
// Dispatchable functions allow users to interact with the pallet and invoke state changes.
// These functions materialize as "extrinsics", which are often compared to transactions.
// Dispatchable functions must be annotated with a weight and must return a DispatchResult.
#[pallet::call]
impl<T: Config> Pallet<T> {
#[pallet::weight(0)]
pub fn create_claim(origin: OriginFor<T>, claim: T::Hash) -> DispatchResult {
// Check that the extrinsic was signed and get the signer.
// This function will return an error if the extrinsic is not signed.
let sender = ensure_signed(origin)?;
// Verify that the specified claim has not already been stored.
ensure!(!Claims::<T>::contains_key(&claim), Error::<T>::AlreadyClaimed);
// Get the block number from the FRAME System pallet.
let current_block = <frame_system::Pallet<T>>::block_number();
// Store the claim with the sender and block number.
Claims::<T>::insert(&claim, (&sender, current_block));
// Emit an event that the claim was created.
Self::deposit_event(Event::ClaimCreated { who: sender, claim });
Ok(())
}
#[pallet::weight(0)]
pub fn revoke_claim(origin: OriginFor<T>, claim: T::Hash) -> DispatchResult {
// Check that the extrinsic was signed and get the signer.
// This function will return an error if the extrinsic is not signed.
let sender = ensure_signed(origin)?;
// Get owner of the claim, if none return an error.
let (owner, _) = Claims::<T>::get(&claim).ok_or(Error::<T>::NoSuchClaim)?;
// Verify that sender of the current call is the claim owner.
ensure!(sender == owner, Error::<T>::NotClaimOwner);
// Remove claim from storage.
Claims::<T>::remove(&claim);
// Emit an event that the claim was erased.
Self::deposit_event(Event::ClaimRevoked { who: sender, claim });
Ok(())
}
}
}
